L-Asparaginase from xylariaceous fungi and application in antitumor activity

Abstract

From 30 xylariaceus fungi isolates, ten were found to produce extracellular L-Asparaginase (ASNase) activity, with Xylaria feejeensis isolate XL001, yielding the highest level. The ASNase activity in the Czapek Dox medium of XL001 was highest with 2.0 g/L glucose and 10 g/L L-asparagine as the carbon, nitrogen sources, respectively. A 42.5 kDa ASNase was enriched 41.4-fold to apparent homogeneity from XL001 cluture media using 80% saturation ammonium sulfate precipitation, DEAE-cellulose anion exchange and Superdex-75 gel filtration chromatography, but at a final yield of only 2.2%, an optimal temperature of 45°C, with >90% activity from -20 to 45°C, a broad pH range of 3.0-11.0 (optimal at pH 5.0). and was sensitive to most divalent cations but especially by Hg²⁺ , CU²⁺ and EDTA. Moreover, relatively strong anti-proliferative activities were found against the five human cell lines with IC₅₀ values ranging from 2.178 ± 0.013 {u1D707}g/mL (breast cancer; BT474) to 7.145 ± 0.009 {u1D707}g/mL (hepatoma cancer; HEP-G2).